For a thin film transistor (TFT) liquid crystal display (LCD), as a high-precision electronic device, defects may occur due to any tiny error. Usually, a TFT-LCD panel includes two substrates arranged opposite to each other to form a cell, i.e., a TFT substrate and a color filter (CF) substrate. A display effect of the TFT-LCD directly depends on an alignment level of the two substrates. When there is a relatively large alignment error, i.e., there is a relatively large offset between the two substrates in each of an X direction and a Y direction, such quality problems as light leakage and display abnormality may occur. Hence, it is necessary to introduce an alignment mark, so as to determine the alignment level of the TFT substrate and the CF substrate.